Dressing unit and method for dressing the flat surface of a grinding wheel

ABSTRACT

A dressing unit for dressing the flat surface of a grinding wheel, the dressing unit having a barrel shape, with sides that are adapted to engage the flat surface of the grinding wheel, with each side having a first end and second end, with each end being chamfered.

BACKGROUND

This disclosure is directed to mechanisms and processes for dressing the flat surface of a grinding wheel, and more particularly, to a dresser unit for dressing the flat surface of a grinding wheel.

As illustrated in FIG. 2, a grinding wheel 104 is a circular disc used for grinding. The grinding wheel 104 is given a continuous rotary movement against a part 112. The grinding wheel remains sharp by cutting away its glazed or loaded grinding surface, thereby exposing sharp new cutting grains to the part. For ease of cutting and proper chip removal, voids are often provided in the grinding wheel.

Although often used by placing an item to be ground against the peripheral edge of the wheel, in other instances the flat surface 100 of the wheel 104 is used. These grinding wheels are most often used in sets on grinding machines 108 called double-disc grinders (see FIGS. 2 and 3) and double-disc grinders are used when parts are ground on both ends or top and bottom, where opposing sides need to be flat and parallel to each other. Springs 112, such as the one shown in FIG. 1, piston rings and valve plates are examples of these parts.

The grinding wheels 104 can be made with resin, epoxy or oxychloride bonds, each having advantages for certain types of parts and grinding processes. Springs are often ground dry and require grinding wheels that stand up to heavy stock removal and the heat generated in the grinding process.

In the production grinding of parts, almost all grinding wheels will need to be dressed and/or trued at some point, so the grinding surface presents a regular flat surface. In the case of spring grinding, as the grinding wheel wears away, the springs begin to lose parallelism or may not be at the proper length. At this point, the grinding wheels need to be dressed flat. Often, the wheels need to have as much as 0.060 inch of wheel shape dressed away to achieve that.

Oxychloride bonded grinding wheels are often used as they are essentially a cement bond that is cured over time before use. Oxychloride bonded wheels that are made with large ceramic grains are pressed to the upper range of hardness, and are extremely difficult to dress.

The most commonly used dresser assembly for dressing these oxychloride bond ceramic grain wheels are a group of metal stars 116, referred to herein as a star dresser 120, on a shaft at the end of a dresser arm 124, as shown in FIG. 4. The group of stars 116 (see FIG. 5) are rubbed back and forth against the grinding wheel face 100 as it is spinning. This breaks out the grains of the grinding wheel 104 under the pressure of the stars 116. This process can take 30 minutes or more and is difficult at best. Because the dresser assembly uses the spinning of the wheel to spin the stars, when the stars near the center of the wheel 104, the speed is reduced and the stars become less effective. This also creates strain on the dresser arm assembly which necessitates the rebuilding of the arm assembly over time. The group of metal stars also leaves an inconsistent dress on the wheel, which is not desirable.

SUMMARY

Disclosed is a dressing unit for dressing the flat surface of a grinding wheel, the dressing unit having a barrel shape, with sides that are adapted to engage the flat surface of the grinding wheel, with each side having a first end and second end, with each end being chamfered.

Also disclosed is a method of dressing the flat surface of the grinding wheel, the method comprising the step of bringing the dressing unit into contact with the flat surface, and the step of rotating under power the dressing unit against the flat surface.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic side view of a conventional spring. The spring top and bottom have been ground level using a grinding wheel (not shown).

FIG. 2 is a schematic side perspective view of two grinding wheels being used to grind the ends of springs positioned between guide bars.

FIG. 3 is a side view of a machine used to grind the ends of the spring shown in FIG. 1. Periodically, a dresser arm assembly on the side of the machine advances a dresser into between the two grinding wheels (not shown) inside the machine in order to dress the flat faces of the grinding wheels.

FIG. 4 is a top perspective view of a portion of the arm of FIG. 3 that includes a conventional star dresser.

FIG. 5 is a top perspective view of several stars used in the star dresser shown in FIG. 4.

FIG. 6 is a side view of an improved arm according to this disclosure for dressing the face of grinding wheels.

FIG. 7 is a top view of the improved arm of FIG. 6.

FIG. 8 is a side view of the dresser barrel of the dresser arm of FIG. 6.

Before one embodiment of the disclosure is explained in detail, it is to be understood that the disclosure is not limited in its application to the details of the construction and the arrangements of components set forth in the following description or illustrated in the drawings. The disclosure is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. Use of “including” and “comprising” and variations thereof as used herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Use of “consisting of” and variations thereof as used herein is meant to encompass only the items listed thereafter and equivalents thereof. Further, it is to be understood that such terms as “forward”, “rearward”, “left”, “right”, “upward”, “downward”, “side”, “top” and “bottom”, etc., are words of convenience and are not to be construed as limiting terms.

DESCRIPTION OF EMBODIMENTS

This disclosure utilizes a steel motorized barrel shaped dressing unit or barrel dresser 130 plated with grit 134 (see FIG. 8). In one embodiment, the grit 134 is diamond. In another embodiment (not shown), the grit is cubic boron nitride. And in other less preferred embodiments (not shown), other grits can be used, as well as other materials for the barrel.

To provide a dressing tool that can be utilized without extensive rebuilding or the additional costs associated with changing grinder parts, the barrel dresser 130 of this disclosure fits a conventional dresser arm 124 at the location where the stars 116 conventionally were attached.

In one embodiment, the barrel dresser 130 is utilized with an air motor 140. This allows the barrel dresser 130 to be used with standard air fittings and pressures commonly found in manufacturing facilities. The barrel dresser 130 can also be used with an electric motor (not shown), to provide specialized controls and functions, where an operator is interested in data provided by the dresser assembly throughout the dressing cycle.

As illustrated in FIGS. 6 and 7, the air motor 140 is connected to the barrel dresser 130 by a drive transmission 144 including a drive shaft 148 connected to a flexible coupling 152, which in turn is connected to a driving bevel gear 156 connected via a driven bevel gear 160 attached to a dresser axle 164 attached to the barrel dresser 130. The dresser axle 164 extends through an opening 166 in the center of the barrel dresser 130, and bearings 170 in each end of the barrel opening 166 support the dresser axle 164. The barrel dresser 130 is mounted on the end of the dresser arm 124, and the air motor 140 and drive transmission 144 are attached to a side of the dresser arm 124.

By providing the appropriate speed and torque, the motorized barrel dresser 130 effectively removes the grinding wheel surface, taking greater depths of cut per pass and in a fraction of the time, as compared to the star dresser 120. Because the barrel dresser 130 is motorized, there is no difference between the dress at the outer portion and the center portion of the grinding wheel face. This produces a more consistent and desirable dress. And because the barrel dresser 130 is plated with grit 134, the barrel dresser 130 can be customized to produce a specific finish on the face of the grinding wheel by using appropriately sized grits and concentrations of diamond particles. Having a motorized barrel dresser also reduces the wear of the dresser arm 124 by reducing the amount of pressure the arm 124 has to apply to the wheel 104 in order to dress the wheel.

Although the barrel dresser 130 was designed to specifically address the problems associate with dressing the most difficult of grinding wheels 104, it can provide similar benefits to grinding wheels of other bonds and compositions.

In other words, disclosed is a method of dressing the flat surface 100 of a grinding wheel 104, the method comprising the step of bringing a barrel shaped dressing unit 130 into contact with the flat surface 100, and the step of rotating under power the dressing unit 130 against the flat surface 100.

The dressing unit has a longitudinal axis defined by the dresser axle 164, and the rotation mechanism comprises the air motor 140 connected to the dressing unit 130 to rotate the dressing unit 130 along its longitudinal axis.

Further, the barrel shaped dressing unit 130 has curved generally parallel sides 174 (see FIG. 8) that are adapted to engage the flat surface 100 of the grinding wheel 104.

The curved sides 174 have a first end 176 and second end 176, and each end is chamfered. By having a barrel shaped, the barrel dresser 130 avoids a sharp edge coming into contact with the grinding wheel face 100, thereby always presenting a predefined dressing surface to the grinding wheel 104.

The disclosed improved dressing unit 130 significantly reduces the conventional dressing time, reduces the need for frequent changing of the dressing assembly parts, and provides a consistent and desirable dress on a grinding wheel face 100.

Various other features of this disclosure are set forth in the following claims. 

1. A method of dressing a flat surface of a grinding wheel, the method comprising the step of bringing a dressing unit into contact with the flat surface, and the step of rotating under power the dressing unit against the flat surface.
 2. A method of dressing the flat surface of the grinding wheel according to claim 1, wherein the dressing unit has a longitudinal axis, and wherein the step of rotating the dressing unit includes connecting a motor to the dressing unit to rotate the dressing unit about its longitudinal axis.
 3. A method of dressing the flat surface of the grinding wheel according to claim 1, wherein the dressing unit is barrel shaped.
 4. A method of dressing the flat surface of the grinding wheel according to claim 3, wherein the barrel shaped dressing unit has sides that are adapted to engage the flat surface of the grinding wheel.
 5. A method of dressing the flat surface of the grinding wheel according to claim 4, wherein the sides each have a first end and second end, and each end is chamfered.
 6. A method of dressing the flat surface of the grinding wheel according to claim 4, wherein the dressing unit sides are plated with a grit.
 7. A method of dressing the flat surface of the grinding wheel according to claim 6, wherein the grit is diamond.
 8. A method of dressing the flat surface of the grinding wheel according to claim 6, wherein the grit is cubic boron nitride.
 9. A dressing unit for dressing the flat surface of a grinding wheel, the dressing unit having a barrel shape, with sides that are adapted to engage the flat surface of the grinding wheel, with each side having a first end and second end, with each end being chamfered.
 10. A dressing unit for dressing the flat surface of a grinding wheel according to claim 9, wherein the dressing unit has sides plated with a grit.
 11. A dressing unit for dressing the flat surface of a grinding wheel according to claim 10, wherein the grit is diamond.
 12. A dressing unit for dressing the flat surface of a grinding wheel according to claim 10, wherein the grit is cubic boron nitride.
 13. A method of dressing a flat surface of a grinding wheel, the method comprising: the step of bringing a barrel shaped dressing unit into contact with the flat surface, the barrel shaped dressing unit having sides that are adapted to engage the flat surface of the grinding wheel, with each side having a first end and second end, with each end being chamfered, the dressing unit having a longitudinal axis, and the step of rotating under power the dressing unit against the flat surface by connecting a motor to the dressing unit to rotate the dressing unit about its longitudinal axis.
 14. A method of dressing the flat surface of the grinding wheel according to claim 13, wherein the grit is diamond.
 15. A method of dressing the flat surface of the grinding wheel according to claim 13, wherein the grit is cubic boron nitride. 